Implantable biocompatible expander suitable for treatment of constrictions of body lumen

ABSTRACT

An implantable biocompatible expander suitable for implantation into a urinary duct, comprises an elongated sinusoidal ring comprising at least two proximal prongs and at least two distal prongs, wherein the expander is resiliently deformable from a relaxed radially expanded orientation to a radially contracted orientation suitable for transluminal delivery through the urinary duct. The expander is configured to exert an outward radial force against a wall of the urinary duct when in-situ within the urinary duct. In particular, the expander is suitable for treatment of benign prostatic hyperplasia and configured for implantation into the prostatic urethra between, and substantially spanning the prostatic urethra between, the bladder neck and external sphincter.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/321,639, filed on Apr. 12, 2016. This application also claimspriority under 35 U.S.C. § 119 or 365 to European Application No. EP15194391.7, filed Nov. 12, 2015. This application also claims thebenefit of U.S. Provisional Application No. 62/254,480, filed on Nov.12, 2015. The entire teachings of the above applications areincorporated herein by reference.

BACKGROUND

Benign prostatic hyperplasia (BPH) involves hyperplasia of prostaticstromal and epithelial cells, resulting in formation of large discretenodules in the transition zone of the prostate gland. When sufficientlylarge, the nodules impinge on the prostatic urethra and increaseresistance to flow of urine from the bladder, causing discomfort for thepatient. Resistance to urine flow requires the bladder to work harderduring voiding, leading to progressive hypertrophy, instability andweakness of the bladder muscle. Various treatments are available forBPH, including medication such as alpha blockers and 5-reductaseinhibitors, clean intermittent self-catheterisation, surgery andminimally invasive therapies such as transurethral microwavethermotherapy and transurethral needle ablation. A further treatmentoption is to implant a stent within the prostatic urethra. One suchstent is described in U.S. Pat. No. 5,269,802 and comprises two ringsconnected by three struts that maintain the two rings in a co-planarrelationship. In use, the larger of the two rings is placed in thebladder and the smaller ring is placed in the prostatic urethra.Prostatic stents can offer immediate relief for symptoms of BPH but theyhave fallen out of favour due a high rate of side effects. They areusually long cylindrical type stents that resemble traditional stentsused in in the heart blood vessels or for peripheral vascular disease.They can migrate from their deployment position and travel to thebladder or to the membranous urethra (up to 12.5% of patients), encrustand block urethra (up to 27.5%), cause incontinence (up to 3%) and pain.Cases of a profound inflammatory response to prostatic stents have beenreported. In total, these combined side effects have historicallyresulted in 8% to 47% of prostatic stents to be removed. In addition,these previous prostatic stents have not had designs which accommodatethe unique characteristics of the prostatic urethra.

WO2015/138763 describes urethral expanders configured for implantationinto the prostatic urethra and in-situ expansion and comprising a numberof spaced apart interconnected circular ring. This device suffers from anumber of drawbacks including: increased encrustation due to thecircumferential disposition of the rings meaning that they will meet theurine at 90°, difficulty in removal due to the rings being embedded at90° to the longitudinal axis of the urethra; the rings impinging on theverumontanum which may block some of the ejaculatory and prostaticducts; the rigidity and static nature of the ring solution impeding thenatural movements of the prostatic urethra during urination andejaculation and causing pain; and the spaced-apart nature of the ringswhich effects non-continuous expansion along the length of the prostaticurethra.

SUMMARY OF THE INVENTION

Broadly, the invention provides a resiliently deformable expander thatin one embodiment is suitable for the treatment of benign prostatichyperplasia (BPH). The expander generally takes the form of a singleelongated undulating ring that is configured for implantation into abody lumen at a target locus that is constricted due to adjacentdiseased tissue. The undulating ring has at least two distal prongs andat least two proximal prongs that are typically configured forinvagination into the wall of the body lumen. The expander is typicallyresiliently deformable in a radial direction between a contractedorientation suitable for transluminal delivery to the target sitethrough the body lumen and an expanded (deployed) orientation configuredto effect in-situ dilation of the body lumen at the target site. Theelongated undulating ring configuration provides minimal contact areabetween the stent and the wall of the body lumen, thereby reducing theextent of potential encrustation. Further, the struts of the undulatingring, due to the elongated undulating ring shape, extend substantiallylongitudinally (as opposed to circumferentially) thereby ensuring thatflow of fluid is along the struts as opposed to at right angles to thestruts for the majority of the exposed surface area. This furtherreduces the incidence of encrustation. The substantially longitudinalnature of the struts will also facilitate easier removal. Furthermore,the undulating ring configuration of the expander allows fordifferential flexing of the expander during use, thus allowing the shapeof the mirror the anatomical shape, and adhere to, and move with, theshape of the wall of the body lumen. In particular, the expander of theinvention does not disrupt the Verumontanum and ejaculatory ducts andits proximal three projections sit anatomically in the triangularlyshaped distal urethra making migration less likely (as well asfacilitating removal). The undulating ring configuration also ensuresthat expansion occurs in the correct anatomical zone of the urethra (inparticular, pushing against the transition zone of the prostate).

The expander of the invention provides a means of dilating a body lumenthat has been constricted due to, for example, a pathological state ordue to trauma. One example of a pathology is benign prostatichyperplasia, a proliferative disease of the prostate gland that causesthe prostate to constrict around, and partially block, the prostaticurethra. Thus, in one embodiment, the invention provides a resilientlydeformable expander for the treatment of benign prostatic hyperplasia(BPH), where the expander takes the form of an undulating (andpreferably sinusoidal) ring that is configured for implantation into theprostatic urethra between the bladder neck and external sphincter, thatin one embodiment substantially spans the prostatic urethra between thebladder neck and external sphincter. In this embodiment, the undulatingring preferably has at least three distal prongs and at least threeproximal prongs that are suitably configured for invagination into thewall of the prostatic urethra, and is ideally resiliently deformablefrom a relaxed radially expanded orientation to a radially contractedorientation suitable for transurethral delivery to a target locus, andwhen in-situ causes dilation of the prostatic urethra allowing urine topass freely through the prostatic urethra thereby addressing a symptomof BPH. In addition, the undulating ring configuration of the expanderprovides minimal contact area between the expander and the wall of theprostatic urethra, thereby minimising risk of the stent obstructing theejaculatory ducts, and also reducing the extent of encrustation. Theundulating ring configuration also allows for the proximal stent to fitsecurely in the distal urethra with the expander's triangular crosssectional shape matching the triangular cross sectional shape of theurethra (with each prong sitting in the most lateral triangular recessesof the urethra. Furthermore, the undulating ring configuration of theexpander allows for differential flexing of the expander during use,thus allowing the shape of the expander adhere to, and move with, theshape of the wall of the wall of the prostatic urethra during exposureto the different forces experienced during urination and ejaculation.(i.e. expansion of the urethra during urination and contraction/spasm ofboth the bladder neck and the distal urethra/external sphincter duringejaculation). The location of the prongs in the triangular recesses willalso allow for normal movement of the urethral wall during contraction.

Accordingly, in a first aspect, the invention provides an implantableexpander suitable for implantation into a body lumen and dilation of aconstricted section of the body lumen, the expander comprising anundulating ring that is typically elongated and comprising at least twoproximal prongs and at least two distal prongs, wherein the expander istypically resiliently deformable and ideally self-expandable from aradially contracted orientation suitable for transluminal deliverythrough the body lumen to a radially expanded orientation, wherein theexpander is configured to span a substantial part of the constrictedsection of the body lumen and cause in-situ expansion of the substantialpart of the constricted section of the body lumen.

The implantable biocompatible expander of the invention is suitable fortreatment of constrictions of various types of body lumen, includingurinary ducts (such as a urethra or ureter), the oesophagus and thegastrointestinal tract. Constrictions may be caused by variouspathologies, including benign and malignant proliferative disorders ofthe adjacent tissue. In a preferred embodiment, the expander isconfigured for use with a urinary duct, for example to dilate a urinaryduct that has been constricted due to growth in the urinary duct or anadjacent tissue.

In one embodiment, the invention provides an implantable biocompatibleexpander suitable for implantation into a urinary duct and dilation of aconstricted section of the urinary duct, the expander comprising anelongated undulating ring comprising at least two proximal prongs and atleast two distal prongs, wherein the expander is resiliently deformableand self-expandable from a radially contracted orientation suitable fortransluminal delivery through the urinary duct to a radially expandedorientation, wherein the expander is configured to span a substantialpart of the constricted section of the urinary duct and cause in-situexpansion of the substantial part of the constricted section of theurinary duct.

The expander of the invention is particularly suitable for treatment ofbenign prostatic hyperplasia (BPH). Thus, in one embodiment, theinvention provides a provides an implantable biocompatible expanderaccording to the invention that is suitable for treatment of benignprostatic hyperplasia, wherein the expander is configured forimplantation into the prostatic urethra between, and spanning asubstantial section of, the prostatic urethra between, the bladder neckand external sphincter, and wherein the expander is resilientlydeformable and self-expandable from a radially contracted orientationsuitable for transluminal delivery through the urethra to a radiallyexpanded orientation.

Preferably, the distal prongs and/or the proximal prongs are configuredfor invagination into the wall of the prostatic urethra,

In one embodiment, the elongated undulating ring comprises at leastthree proximal prongs and at least three distal prongs.

In one embodiment, the undulating ring comprises three or five distalprongs and three or five proximal prongs.

In one embodiment, the undulating ring comprises three distal prongs andthree proximal prongs. When the indication to be treated is BPH, the useof three distal and proximal prongs is ideal as the expander will have asubstantially triangular cross-section which matches the cross sectionof the prostatic urethra.

In one embodiment, the undulating ring comprises five distal prongs andfive proximal prongs.

In one embodiment, the undulating ring comprises seven distal prongs andseven proximal prongs.

In one embodiment, the undulating ring is a sinusoidal ring.

The undulating ring typically comprises elongated struts connecting thedistal and proximal prongs and open areas between the struts and prongs.Suitably the radially outwardly facing surface of the prongs and strutsis less than 10% of the total open areas. Suitably the radiallyoutwardly facing surface of the prongs and struts is less than 7% of thetotal open areas. Suitably the radially outwardly facing surface of theprongs and struts is less than 5% of the total open areas. Suitably theradially outwardly facing surface of the prongs and struts is less than3% of the total open areas.

In one embodiment, the prongs are substantially V-shaped. In anotherembodiment, the prongs are substantially U-shaped. In anotherembodiment, the prongs are substantially rectangular shaped.

In one embodiment, the elongated struts of each prong are substantiallystraight. In another embodiment, the elongated struts of each prong aresubstantially curved. In one embodiment, the elongated struts of eachprong are curved substantially outwardly. In one embodiment, theelongated struts of each prong are curved substantially outwardly. Inone embodiment, at least one elongated strut is curved substantiallyoutwardly and at least one elongated strut is curved substantiallyinwardly.

In one embodiment of the invention, an apex of one of more of the prongscomprises a loop or lip. Typically, the loop or lip projects radiallyinto the expander (i.e. the ends of the prongs flare inwardly). Inanother embodiment, the loop or lip projects radially out of theexpander (i.e. the ends of the prongs flare inwardly).

In one embodiment, the apices of the distal prongs are unconnectedcircumferentially. In one embodiment, the apices of the proximal prongsare unconnected circumferentially.

In one embodiment, the prongs are longitudinally staggered with respectto each other. In one embodiment, the prongs are longitudinallystaggered with respect to each other at a distal end of the expander. Inanother embodiment, the prongs are longitudinally staggered with respectto each other at a proximal end of the expander. In another embodiment,the prongs are longitudinally staggered with respect to each other atboth ends of the expander.

In one embodiment, an apex of the distal prongs comprises a loop or lipthat projects generally radially into the expander and an apex of theproximal prongs comprises a loop or lip that projects generally radiallyout of the expander. In another embodiment, an apex of the distal prongscomprises a loop or lip that projects generally radially out of theexpander and an apex of the proximal prongs comprises a loop or lip thatprojects generally radially into the expander.

In one embodiment of the invention, an apex of one of more of the prongsis substantially M-shaped.

In one embodiment, the expander is formed from a wire, for examplenitinol wire. The wire can have any profile, for example circular, oval,rectangular, square, or otherwise. In a preferred embodiment, theprofile is circular. The expander may also be formed by a ribbon. Also,it can be formed by any process, for example cutting from a tubularstructure. In a preferred embodiment, the expander is formed by lasercutting. In one embodiment, the expander comprises an anchoring elementfor anchoring the expander in-situ within a body lumen. In oneembodiment, the expander comprises at least two anchoring elements. Inone embodiment, the at least two anchoring elements project in differentdirections. In one embodiment, the expander comprises at least oneanchoring element disposed at a proximal end of the expander and atleast one anchoring element disposed at a distal end of the expander. Inone embodiment, the anchoring element comprises a projection, forexample a hook, barb, coil, or screw. In one embodiment of the inventionthe undulating or sinusoidal ring comprises a single wire, typicallyhaving ends that are joined at or close to each end. In one embodimentof the invention, one of the ends of the wire is shaped to form theanchoring element. In one embodiment of the invention, the anchoringelement comprises an end of the wire that extends beyond a joiningpoint. In one embodiment of the invention, each end of the wire extendsbeyond a joining point, typically co-extensive with the strut of theexpander. In one embodiment, the or each anchoring element, or at leasta part thereof, is biodegradable. This allows the anchoring element (ora part thereof) biodegrade over time, allowing for ease of removal afterthe anchoring element has degraded.

In one embodiment, the anchoring element comprises a collar that isconfigured to embrace a strut and one or more projections extending fromthe collar. In one embodiment, the projections are disposed on each endof the collar. In one embodiment, projections are disposed on oppositesides of the collar. In one embodiment, the or each projection is abarb.

In one embodiment, the elongated sinusoidal ring is cylindrical,conical, frusto-conical, tapers inwardly at each end (i.e. barrelshaped), or tapers inwardly towards in mid-section (i.e. has a waist).

In one embodiment, the expander is adapted to elute a pharmaceuticallyactive agent. Examples of pharmaceutically active agents include tissuegrowth inhibitors such as alpha reductase inhibitors or cellproliferation inhibitors such as paclitaxel. Methods of incorporatingdrugs into the expander for in-vivo elution will be apparent to a personskilled in the art and are described in, for example, U.S. Pat. Nos.5,591,277, 5,697,967, 5,599,325, US2007/0077266, WO0112779 andWO9013332.

In another aspect, the invention provides an implantable biocompatibleexpander to treat BPH, wherein the expander:

is configured for resilient deformation and self-expansion from aradially contracted orientation suitable for transluminal deliverythrough a urinary duct (in particular through a urethra) to a radiallyexpanded orientation capable of effecting in-situ dilation of theprostatic urethra;

is typically configured to fit within the prostatic urethra between thebladder neck and the external sphincter without blocking theverumontanum;

is typically configured to anatomically conform to the wall of prostaticurethra; and

typically comprises a plurality of longitudinal struts and is typicallyfree of circumferential struts.

In another aspect, the invention provides an elongated, indwelling,expander ring to treat BPH, the expander ring configured to fit withinthe prostatic urethra between the bladder neck and the externalsphincter without blocking the verumontanum and effect in-situ dilationof the prostatic urethra.

In another aspect, the invention provides an elongated, indwelling,expander ring to treat BPH, the expander ring comprising a plurality oflongitudinal struts and typically no circumferential struts configuredto allow the expander conform to the anatomy of the prostatic urethrawhen expanded without blocking the verumontanum.

In one embodiment, the distal end of the expander is configured toengage the wall of the distal prostatic urethra without obstructing theverumontanum.

In one embodiment, the longitudinal struts on a distal end of theexpander are configured to engage the wall of the distal prostaticurethra without obstructing the verumontanum.

In one embodiment, the proximal end of the expander is configured toengage the wall of the proximal prostatic urethra adjacent thetransition zone of the prostate gland.

In one embodiment, the longitudinal struts on a proximal end of theexpander are configured to engage the wall of the proximal prostaticurethra adjacent the transition zone of the prostate gland.

In one embodiment, the longitudinal struts are configured fordifferential flexing of the expander during use (differential flexing ofthe distal and proximal ends of the expander), thus allowing the shapeof the expander adhere to, and move with, the shape of the wall of thebody lumen.

In one embodiment, the longitudinal struts are formed by an undulatingstructural element, for example a sinusoidal structural element. In oneembodiment, the structural element is a wire or a ribbon, for example ametal wire or ribbon.

In one embodiment, the expander comprises an elongated ring. In oneembodiment, the elongated ring is formed from an undulating structuralelement, typically a single undulating structural element. In oneembodiment, the elongated ring is formed from expansible mesh.

In another aspect, the invention provides a delivery device for anexpander of the invention comprising a handle operatively connected to adelivery tube having a hollow distal end remote from the handleconfigured to receive an expander of the invention in a contractedorientation, and an ejection element operatively connected to the handleand operable to eject the expander from the open end of the deliverytube. In one embodiment, the delivery tube is configured for insertioninto the urethra through the penis and for delivery of an expander ofthe invention into the prostatic urethra. In another embodiment, thedelivery tube is configured for insertion into the oesophagus throughthe mouth and for delivery of an expander of the invention into theoesophagus. In another embodiment, the delivery tube is configured forinsertion into the colon through the anus and for delivery of anexpander of the invention into the colon. In one embodiment, theejection element comprises a head configured to engage a proximal end ofthe expander. This allows the ejection element grip the expander andeffect movement of the expander proximally (towards thehandle—retraction) and distally (away from the handle—ejection). In oneembodiment, the head of ejection element comprises a jig configured toengage the apex of at least one of the proximal prongs. In oneembodiment, the head of ejection element comprises a jig configured toengage the apex of all of the proximal prongs, for example two, three,five or seven proximal prongs. In one embodiment, the head of theejection element is configured to extend into a lumen of the proximalend of the expander. In one embodiment, the head of the ejection elementhas a cross-sectional area that matches the cross-sectional area of thebody lumen of the lumen into which the expander is to be inserted. This,when the expander is radially contracted and inserted into the open endof the delivery tube, the head of the ejection element is inserted intothe lumen of the proximal end of the expander, forcing the expander toassume the cross-sectional shape of the head. In the case of theprostatic urethra, the head of the ejection element typically has asubstantially triangular cross section, and this forces the expander toassume a generally triangular cross-sectional shape, substantiallymatching the cross-sectional shape of the prostatic urethra. In oneembodiment, the head of the ejection element has a substantiallypentagonal cross section. In one embodiment, the head of the ejectionelement has a substantially heptagonal cross section.

In one embodiment, the delivery device comprises an imaging devicedisposed within the hollow distal end of the delivery tube andconfigured for imaging the placement of the expander. In one embodimentthe imaging device is disposed within a lumen of the delivery tube. Inone embodiment the imaging device is disposed concentrically within thelumen of the delivery tube. In one embodiment, the imaging devicecomprises a light source configured to illuminate, in use, a part of thebody lumen adjacent the end of the delivery device. In one embodiment,the imaging device is a cystoscope.

In another aspect, the invention relates to a method of treating adisease or condition characterised by constriction of a body lumen in amammal, which method employs an implantable expander (typically animplantable expander of the invention), the method comprising the stepsof implanting the expander into a constricted section of the body lumen,whereby the expander in the expanded orientation effects in-situdilation of the constricted section of the body lumen.

In one embodiment, the method comprises the steps of:

delivering the expander in a radially contracted orientation through thebody lumen to a target location within the body lumen characterised by aconstricted section of the body lumen; and

allowing the expander expand at the target location to a radiallyexpanded orientation against the wall of the body lumen, whereby theexpander in the expanded orientation effects in-situ dilation of theconstricted section of the body lumen.

In one embodiment, the disease or condition characterised byconstriction of a body lumen in a mammal is a proliferative disease ofthe urethra.

In one embodiment, the proliferative disease of the urethra is benignprostatic hyperplasia.

In one embodiment, the expander is configured for resilient deformationand self-expansion from a radially contracted orientation suitable fortransluminal delivery through a urinary duct to a radially expandedorientation capable of effecting in-situ dilation of the prostaticurethra

In one embodiment, the method of the invention employs a delivery deviceconfigured to hold the expander in a radially contracted orientation,deliver the expander through the body lumen to the constricted sectionof the body lumen in the radially contracted orientation, and releasethe expander at the constricted section of the body lumen.

In one embodiment, the delivery device comprises a handle includingactuation means configured to remotely release the expander, in whichthe method includes a step of actuating the actuation means of thedelivery device to remotely release the expander at the target locationwithin the prostatic urethra.

In one embodiment, the method of the invention additionally employs animaging device suitable for providing an image of the constrictedsection of the body lumen, the method comprising the using the imagingdevice to correctly position the expander at the constricted section ofthe body lumen.

In one embodiment, the positioning step comprising longitudinaladjustment of the position of the expander within the body lumen.

In one embodiment, the positioning step comprising radial adjustment ofthe position of the expander within the body lumen.

In one embodiment, the delivery device comprises a light at a distal endthereof, wherein the step of delivering the expander to the targetlocation includes a step of guiding the delivery device and expander tothe target location in the body lumen by external monitoring of theposition of the light.

In one embodiment, the expander is an expander according to theinvention.

In another aspect, the invention relates to a method of treating benignprostatic hyperplasia in a mammal, which method employs an implantablebiocompatible expander configured for resilient deformation andself-expansion from a radially contracted orientation suitable fortransluminal delivery through a urinary duct to a radially expandedorientation capable of effecting in-situ dilation of the prostaticurethra, wherein the expander is configured to fit within the prostaticurethra between the bladder neck and the external sphincter, the methodcomprising the steps of implanting the expander into the prostaticurethra at a target location between the bladder neck and the externalsphincter, whereby the expander in the radially expanded orientationeffects in-situ dilation of the prostatic urethra between the bladderneck and the external sphincter.

In one embodiment, the method comprises the steps of:

delivering the expander in a radially contracted orientation through theurethra to the target location within the prostatic urethra between thebladder neck and the external sphincter; and

allowing the expander expand at the target location to a radiallyexpanded orientation against the wall of the prostatic urethra.

In one embodiment, the expander is configured to effect in-situ dilationof the prostatic urethra at the target location without blocking theverumontanum.

In one embodiment, the expander is configured to fit in the prostaticurethra between the bladder neck and the external sphincter withoutinhibiting the function of the bladder neck.

In one embodiment, the expander is configured to fit in the prostaticurethra between the bladder neck and the external sphincter withoutinhibiting the function of the bladder neck and the external sphincter.

In one embodiment, the expander is configured to anatomically conform tothe wall of the prostatic urethra.

In one embodiment, the expander is resiliently deformable to conform tothe wall of the prostatic urethra as the shape and topography of thewall changes during, for example, urination or ejaculation.

In one embodiment, the method of the invention employs a delivery deviceconfigured to hold the expander in a radially contracted orientation,deliver the expander through the urethra to the prostatic urethra in theradially contracted orientation, and release the expander in theprostatic urethra whereby upon release the expander self-expands to theradially expanded orientation.

In one embodiment, the delivery device comprises a handle includingactuation means configured to remotely release the expander, in whichthe method includes a step of actuating the actuation means of thedelivery device to remotely release the expander within the prostaticurethra.

In one embodiment, the expander is configured to span a substantialsection of the prostatic urethra between the bladder neck and theexternal sphincter.

In one embodiment of a method of the invention, the expander isconfigured to anatomically conform to the lumen of the prostaticurethra.

In one embodiment, the expander is configured to dilate the prostaticurethra without blocking the verumontanum. For example, the expander maycomprise a configuration of struts that provides an opening dimensionedto overlap with the verumontanum.

In one embodiment, the expander has a longitudinal dimension of 15 mm to35 mm.

In one embodiment, the delivery device comprises a light at a distal endthereof, wherein the step of delivering the expander to the prostaticurethra includes a step of guiding the delivery device by externalmonitoring of the position of the light. such that the expander islocated between the bladder neck and the external sphincter.

In one embodiment, the implantable expander is an implantable expanderof the invention.

In one embodiment, the implantable expander employed in the method ofthe invention comprises a hollow lumen and is configured for resilientdeformation and self-expansion from a radially contracted orientationsuitable for transluminal delivery through the urinary duct to aradially expanded orientation, wherein the expander is configured to fitwithin the prostatic urethra between the bladder neck and the externalsphincter and span a substantial section of the prostatic urethrawithout blocking the verumontamum, the method comprising the steps of:

delivering the expander in radially contracted orientation through theurethra to a target location within the prostatic urethra between thebladder neck and the external sphincter; and

allowing the expander expand at the target location to a radiallyexpanded orientation against the wall of the prostatic urethra, wherebythe expander in the expanded orientation effects in-situ dilation of theprostatic urethra at the target location without blocking theverumontanum and preserves the function of the bladder neck.

In one embodiment, in-situ expansion of the expander includes a step ofplacing a radially expansible member in the lumen of the expander andradially expanding the member to effect expansion of the expander in theprostatic urethra. The radially expansible member may be a balloon.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing will be apparent from the following more particulardescription of example embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingembodiments of the present invention.

FIG. 1 is an elevational view of a three-prong expander of the inventionin a relaxed, expanded, state;

FIG. 2 is an elevational view of a three-prong expander of FIG. 1 in acontracted state;

FIG. 3 is a partly sectional view of the expander of FIG. 1 disposedwithin the prostatic urethra of a patient with benign prostatichyperplasia in which the expander is exerting an outward radial pressureon the walls of the prostatic urethra causing dilation;

FIG. 4 is a partly sectional view similar to FIG. 2 showing the seminalvesicle and an ejaculatory duct entering the prostatic urethra;

FIG. 5 is a photograph of an expander of the invention in-situ within aprostatic urethra showing the three proximal prongs and three distalprongs;

FIG. 6 is an elevational view of a five-prong expander according to theinvention;

FIG. 7 is an elevational view of a three prong expander according to theinvention comprising a tapered sinusoidal ring;

FIG. 8 is an elevational view of a three prong expander according to theinvention comprising a barrel-shaped sinusoidal ring;

FIG. 9 is an elevational view of a three prong expander according to theinvention comprising in which the apices of the prongs are flaredoutwardly;

FIG. 10 is an elevational view of a three prong expander according tothe invention in which the apices of the distal prongs are flaredoutwardly;

FIG. 11 is an elevational view of a three prong expander according tothe invention in which the apices of the distal prongs comprise aninwardly flared loop and the apices of the proximal prongs comprise anoutwardly flared loop;

FIG. 12 is an elevational view of a three prong expander according tothe invention similar to the expander of FIG. 12 and in which the distalprongs are offset in height and the proximal prongs are offset in heightto allow the distal and proximal loops dovetail when the expander is ina contracted orientation;

FIG. 13 is an elevational view of the three-prong expander of FIG. 12shown in a contracted orientation;

FIG. 14 is an elevational view of a three-prong expander of theinvention having looped apices on the distal and proximal prongs;

FIG. 15 is an elevational view of a three prong expander of theinvention in which the struts of the distal prongs have a greaterthickness that the struts of the proximal prongs;

FIG. 16 is an elevational view of a three prong expander of theinvention in which the apices of the distal prongs are formed into anM-formation, and in which an end of the wire extends beyond one of theapices to provide a fixation barb;

FIG. 17 is an elevational view of a three-prong expander of theinvention in which an end of the wire extends beyond one of the apicesto provide a coil having a barbed end;

FIG. 18 is an elevational view of a three-prong expander of theinvention in which each end of the wire extends longitudinally beyondthe ends of the expander to provide distal and proximal barbs;

FIG. 19 is an elevational view of the three-prong expander of FIG. 1having an anchoring element disposed on one of the longitudinal struts;

FIG. 20 is an elevational view of a three-prong expander of theinvention in which each end of the wire extends longitudinally beyondthe ends of the expander to provide distal and proximal barbs thatextend circumferentially partially around each end of the expander;

FIG. 21 is an elevational view of a three-prong expander of theinvention in which four of the struts are substantially linear and fourof the struts are non-linear;

FIG. 22 is an elevational view of a two-prong expander of the inventionshown in a relaxed expanded state;

FIG. 23 is an elevational view of the two-prong expander of FIG. 22 inwhich two of the longitudinal prongs comprise anchoring elements;

FIG. 24 is an elevational view of an alternative embodiment of two-prongexpander of the invention shown in a relaxed expanded state;

FIG. 25 is an elevational view of an anchoring element shown disposed ona strut of an expander of the invention;

FIG. 26 is an elevational view of a further embodiment of anchoringelement shown disposed on a strut of an expander of the invention;

FIG. 27 is an elevational view of a further embodiment of anchoringelement shown disposed on a strut of an expander of the invention;

FIG. 28 is an elevational view of a further embodiment of anchoringelement shown disposed on a strut of an expander of the invention;

FIG. 29 is an elevational view of a delivery device for an expander ofthe invention prior to insertion of the expander;

FIG. 30 is an elevational view of the delivery device of FIG. 20 showingthe expander in-situ within the distal end of the device in a contractedorientation;

FIG. 31 is an elevational view of the delivery device of FIG. 20 showingthe expander in-situ within the prostatic urethra after ejection fromthe distal end of the device; and

FIG. 32 is an elevational view of a distal end of an ejection elementforming part of the delivery device of FIG. 29.

FIG. 33 (A to D) illustrate a delivery device of the inventionincorporating a cystoscope disposed concentrically with a lumen of thedelivery device in use delivering an expander of the invention in theprostatic urethra.

FIG. 34 is a 3-D X-ray image showing an expander of the inventionin-situ in the prostatic urethra of a canine.

FIGS. 35 and 36 are photographs showing an expander of the inventiondeployed in the prostatic urethra of a canine. The verumontanum is theridge at six o'clock in the photos.

FIG. 37 illustrates a method of treating benign prostatic hyperplasia(BPH).

FIG. 38 illustrates an expander of the invention deployed in theprostatic urethra of a patent with BPH, between the bladder neck muscleand the external sphincter. This figure shows how the deviceaccommodates the verumontanum between two prongs of the expander in thedistal prostatic urethra, which the proximal end of the device isconfigured such that one of the prongs pushes the transition zone of theprostate gland away from the lumen of the prostatic urethra.

DETAILED DESCRIPTION OF THE INVENTION

A description of example embodiments of the invention follows.

The teachings of all patents, published applications and referencescited herein are incorporated by reference in their entirety.

Where used herein and unless specifically indicated otherwise, thefollowing terms are intended to have the following meanings in additionto any broader (or narrower) meanings the terms might enjoy in the art:

Unless otherwise required by context, the use herein of the singular isto be read to include the plural and vice versa. The term “a” or “an”used in relation to an entity is to be read to refer to one or more ofthat entity. As such, the terms “a” (or “an”), “one or more,” and “atleast one” are used interchangeably herein.

As used herein, the term “comprise,” or variations thereof such as“comprises” or “comprising,” are to be read to indicate the inclusion ofany recited integer (e.g. a feature, element, characteristic, property,method/process step or limitation) or group of integers (e.g. features,element, characteristics, properties, method/process steps orlimitations) but not the exclusion of any other integer or group ofintegers. Thus, as used herein the term “comprising” is inclusive oropen-ended and does not exclude additional, unrecited integers ormethod/process steps.

As used herein, the term “disease” is used to define any abnormalcondition that impairs physiological function and is associated withspecific symptoms. The term is used broadly to encompass any disorder,illness, abnormality, pathology, sickness, condition or syndrome inwhich physiological function is impaired irrespective of the nature ofthe aetiology (or indeed whether the aetiological basis for the diseaseis established). It therefore encompasses conditions arising frominfection, trauma, injury, surgery, radiological ablation, poisoning ornutritional deficiencies.

As used herein, the term “treatment” or “treating” refers to anintervention (e.g. the administration of an agent to a subject) whichcures, ameliorates or lessens the symptoms of a disease or removes (orlessens the impact of) its cause(s) (for example, the reduction inaccumulation of pathological levels of lysosomal enzymes). In this case,the term is used synonymously with the term “therapy”.

Additionally, the terms “treatment” or “treating” refers to anintervention (e.g. the administration of an agent to a subject) whichprevents or delays the onset or progression of a disease or reduces (oreradicates) its incidence within a treated population. In this case, theterm treatment is used synonymously with the term “prophylaxis”.

As used herein, an effective amount or a therapeutically effectiveamount of an agent defines an amount that can be administered to asubject without excessive toxicity, irritation, allergic response, orother problem or complication, commensurate with a reasonablebenefit/risk ratio, but one that is sufficient to provide the desiredeffect, e.g. the treatment or prophylaxis manifested by a permanent ortemporary improvement in the subject's condition. The amount will varyfrom subject to subject, depending on the age and general condition ofthe individual, mode of administration and other factors. Thus, while itis not possible to specify an exact effective amount, those skilled inthe art will be able to determine an appropriate “effective” amount inany individual case using routine experimentation and background generalknowledge. A therapeutic result in this context includes eradication orlessening of symptoms, reduced pain or discomfort, prolonged survival,improved mobility and other markers of clinical improvement. Atherapeutic result need not be a complete cure.

In the context of treatment and effective amounts as defined above, theterm subject (which is to be read to include “individual”, “animal”,“patient” or “mammal” where context permits) defines any subject,particularly a mammalian subject, for whom treatment is indicated.Mammalian subjects include, but are not limited to, humans, domesticanimals, farm animals, zoo animals, sport animals, pet animals such asdogs, cats, guinea pigs, rabbits, rats, mice, horses, cattle, cows;primates such as apes, monkeys, orangutans, and chimpanzees; canids suchas dogs and wolves; felids such as cats, lions, and tigers; equids suchas horses, donkeys, and zebras; food animals such as cows, pigs, andsheep; ungulates such as deer and giraffes; and rodents such as mice,rats, hamsters and guinea pigs. In preferred embodiments, the subject isa human.

“Implantable” as applied to an expander of the invention means a devicethat is formed of materials that are biocompatible, i.e. do not normallypromote an immune response in the host and/or cause trauma, inflammationor scarring. Examples of such materials include gold, titanium,cobalt-chromium alloy, tantalum alloy, nitinol, and several polymers.

“Expander” means a biocompatible device having a lumen to allow for flowof liquid past the expander and that is resiliently deformable andself-expandable between a relaxed, expanded orientation and a contractedorientation suitable for transluminal delivery, and sometimespercutaneous delivery, whereby when in-situ the expander exerts anoutward radial force against the walls of the body lumen. The expanderusually take a generally cylindrical form and may be configured toconform to the shape of a section of a body lumen. Expanders for bodylumen such as arteries, veins and urethras are known in the literature,for example WO2015138763, CN202822454, and U.S. Pat. No. 5,269,802. Theexpander may be made from any suitable material for example stainlesssteel, a shape memory polymer (for example a linear block copolymer orother thermoplastic polymers having shape memory effect), and a shapememory alloy (i.e. nitinol).

“Body lumen” means an elongated tubular organ within the body, includingurinary ducts, gastrointestinal tract, oesophagus, and vasculature.“Urinary duct” means a urethra or ureter.

“Undulating ring” means a ring shaped device formed from a structuralelement such as a wire shaped in a wave-like form and having at leasttwo distal prongs and at least two proximal prongs (see FIGS. 1 to 24).The undulating structural element may take a substantially sinusoidalwave form (a sinusoidal ring), a substantially square wave form (asquare wave ring), a wave form that is intermediate a sinusoidal waveform and square wave form, and any combination of these wave forms. Inone embodiment, the undulating ring has a substantially periodic waveform. In one embodiment, the undulating ring has a non-periodic waveform. In one embodiment, the prongs are substantially V-shaped. In oneembodiment, the prongs are substantially rectangular shaped. In apreferred embodiment, the undulating ring is a sinusoidal ring. In apreferred embodiment, the undulating ring has three distal prongs andthree proximal prongs. An undulating ring having three distal andproximal prongs is particularly suitable for treatment of benignprostatic hyperplasia. In one embodiment, at least one of the prongsforms two or more sub-prongs, for example a prong may be W-shaped toform two sub-prongs. In one embodiment, the undulating ring has a width(in a relaxed state) that is greater than the width of the diseasedprostatic urethra. In one embodiment, the undulating ring has a width(in a relaxed state) that is 5-40% greater than the width of thediseased prostatic urethra. In one embodiment, the undulating ring has awidth (in a relaxed state) that is 10-30% greater than the width of thediseased prostatic urethra.

“Elongated undulating ring” means an undulating ring that has alongitudinal dimension that is equal to or greater than its maximaltransverse dimension when in a relaxed, expanded, state. Typically, themaximal longitudinal dimension is greater than its maximal transversedimension when in a relaxed, expanded, state. Generally, the undulatingring has a length of 10-45 mm. Typically, the undulating ring has awidth (in a relaxed state) of 6-30 mm. In one embodiment, the undulatingring has a length of 15-25 mm. In one embodiment, the undulating ringhas a width (in a relaxed state) of 10-20 mm. In one embodiment, thelength of the undulating ring is at least 10% greater than the width ofthe undulating ring (in a relaxed state). In one embodiment, the lengthof the undulating ring is at least 20% greater than the width of theundulating ring (in a relaxed state). In one embodiment, the length ofthe undulating ring is at least 30% greater than the width of theundulating ring (in a relaxed state). In one embodiment, the length ofthe undulating ring is at least 40% greater than the width of theundulating ring (in a relaxed state). In one embodiment, the length ofthe undulating ring is 1-40% greater than the width of the undulatingring (in a relaxed state). In one embodiment, the length of theundulating ring is 5-40% greater than the width of the undulating ring(in a relaxed state). In one embodiment, the length of the undulatingring is 5-30% greater than the width of the undulating ring (in arelaxed state). In one embodiment, the length of the undulating ring is5-20% greater than the width of the undulating ring (in a relaxedstate).

“Proximal prongs” refers to the prongs that are disposed at the deliveryside of the body lumen when the expander is in-situ within the bodylumen. “Distal prongs” refers to the prongs that are disposed oppositeto the delivery side of the body lumen when the expander is in-situwithin the body lumen. In the case of an extender of the invention forthat is configured for treatment of BPH, the proximal prongs willtypically lie adjacent to the external sphincter, and the distal prongswill typically lie adjacent to the bladder neck.

“Resiliently deformable and self-expandable” means that the expander canbe radially compressed into a contracted orientation (suitable fortransluminal delivery) and upon release of the compression forces willassume a relaxed expanded orientation. In this manner, the expander isdelivered using a suitable delivery vehicle in a contracted orientationand the compression forces are released in-situ at a target siteallowing the expander exert outward radial forces against the wall ofthe body lumen. Generally, the width of the expander in the relaxedstate is greater than the width of the target body lumen. Variousdelivery means are suitable, for example a delivery tube having a hollowtip dimensioned to receive and hold the expander in a contractedorientation, whereby upon ejection from the delivery tube the expanderexpands. Other delivery means include a catheter having an outer sheaththat during delivery embraces the expander and when in-situ is withdrawnallowing the expander expand. In one embodiment, the expander can becontracted to a cross-sectional area of less than 50% of thecross-sectional area of the expander in its relaxed state. In oneembodiment, the expander can be contracted to a cross-sectional area ofless than 40% of the cross-sectional area of the expander in its relaxedstate. In one embodiment, the expander can be contracted to across-sectional area of less than 30% of the cross-sectional area of theexpander in its relaxed state. In this regard, “cross-sectional area”means a cross-section area taken through a mid-point of the expander anddefined by the longitudinal struts.

“Radially contracted orientation suitable for transluminal delivery”means that the expander is radially contracted to bring the prongs closetogether thereby significantly reducing the transverse profile of thering such that it can be delivered through the body lumen.

“Relaxed radially expanded orientation” means that the profile of theexpander when it is in a relaxed state.

“Substantial section of the prostatic urethra” means at least 30% of thelength of the prostatic urethra between the bladder neck and externalsphincter. In one embodiment, the undulating ring is configured to spanat least 40% of the length of the prostatic urethra between the bladderneck and external sphincter. In one embodiment, the undulating ring isconfigured to span at least 50% of the length of the prostatic urethrabetween the bladder neck and external sphincter. In one embodiment, theundulating ring is configured to span at least 60% of the length of theprostatic urethra between the bladder neck and external sphincter. Inone embodiment, the undulating ring is configured to span at least 70%of the length of the prostatic urethra between the bladder neck andexternal sphincter.

“Self-expansion” as applied to the resiliently deformable expander meansthat the expander is adjustable between a radially expanded and aradially contracted configuration and biased into the radially expandedconfiguration.

“Disease or condition characterised by constriction of a body lumen in amammal” means for example proliferative conditions such as benignprostatic hyperplasia, or other proliferative or non-proliferativeconditions such as inflammation, associated with a body lumen and whichcause constriction or mis-shaping, and partial or complete blockage ofthe body lumen. In one embodiment the body lumen is a body lumen of therenal system, for example a urethra or ureter. In one embodiment, themammal is a human for example a male human or a female human. In oneembodiment, the condition is inflammation of the body lumen. In oneembodiment, the condition is inflammation of the ureter or urethra (forexample caused by trauma or a renal stone). In one embodiment, thecondition is incontinence, for example stress urinary incontinence. Inthis embodiment, the expander is generally placed in the urethra betweenthe bladder neck and the external sphincter (typically for the purposeof re-shaping the prostatic urethra).

“Target location” as applied to a method of treating benign prostatichyperplasia means a section of the prostatic urethra between the bladderneck and the external sphincter that spans a substantial section of theprostatic urethra including a constricted section. Typically, the targetlocation is spaced at least 5 mm from both the external sphincter andthe bladder neck. Typically, the target location is spaced at least 10mm from both the external sphincter and the bladder neck.

“Without inhibiting the function of the bladder neck” as applied to theexpander means that the expander when correctly positioned in theprostatic urethra between the bladder neck and the external sphincterdoes not affect the functioning of the bladder neck allowing the neckopen and close in a normal manner during urination and tonicallycontract during ejaculation.

“Without inhibiting the function of the external sphincter” as appliedto the expander means that the expander when correctly positioned in theprostatic urethra between the bladder neck and the external sphincterdoes not affect the functioning of the external sphincter allowing thesphincter to rhythmically contract/spasm during ejaculation. This is themuscle that propels the ejaculate in the normal antegrade fashion (thespasm of the external sphincter in conjunction with the tight closing ofthe bladder neck means the ejaculate is propelled forward to the penis).

“Verumontanum” (or seminal colliculus) is a distinctive median elevationon the posterior wall of the prostatic urethra. It is an importantlandmark as it contains the slit-like openings of the ejaculatory ducts(containing semen) and the openings of the prostatic ducts (containingprostatic fluid).

“Without blocking the nerumontanum” as applied to the expander meansthat the expander is configured such that when it is deployed in anexpanded orientation within the prostatic urethra between the bladderneck and external sphincter it does not block the verumontanum andlessens or completely avoidsdisruption, compression or damage of theVerumontanum that can cause dysfunction in emission of semen into theprostatic urethra.

“Imaging device” means a device that can remotely image the urethra fromoutside the body. Examples include ultrasound and CT scanners.

“Anatomically conform” as applied to the expander means that theexpander is configured to confirm to the wall of the prostatic urethra.In one embodiment, it means that the expander is deformable to conformto the wall of the prostatic urethra as the shape and topography of thewall changes during, for example, urination or ejaculation.

Examplification:

The invention will now be described with reference to specific Examples.These are merely exemplary and for illustrative purposes only: they arenot intended to be limiting in any way to the scope of the monopolyclaimed or to the invention described. These examples constitute thebest mode currently contemplated for practicing the invention.

Referring to the drawings, and initially to FIG. 1, there is illustratedan expander according to the invention indicated generally by thereference numeral 1. The expander 1 comprises a single nitinol wireconfigured as an elongated sinusoidal ring having a distal end 3comprising three distal prongs 4 with apices 5 and a proximal end 6having three proximal prongs 7 with apices 8. The prongs are connectedby longitudinal struts 9. The expander 1 is shown in an expanded,relaxed, state and has a length of approximately 22 mm and a width ofapproximately 15 mm. In the expanded state shown, the distance betweenthe apices 5 of adjacent distal prongs 4 at the distal end 3 of theexpander is approximately 14 mm. Likewise, the distance between theapices 8 of adjacent proximal prongs 7 at the proximal end 6 of theexpander is approximately 14 mm. The nitinol wire has a cross-sectionaldiameter of approximately 0.4 mm.

Referring to FIG. 2, the expander 1 is shown in a radially contractedstate in which the distal and proximal prongs are brought together. Inthis contracted state, the cross-sectional area of the expander isreduced by more than 70% compared with the relaxed expanded state shownin FIG. 1, and the distance between adjacent distal and proximal prongshas reduced from 14 mm to 4-5 mm. In this contracted configuration, theresilient deformability of the sinusoidal ring configuration causes thering to exert an outward radial force.

Referring to FIGS. 3 and 4 there is illustrated an expander of FIG. 1shown in use in the treatment of benign prostatic hyperplasia. Theexpander 1 is disposed within the prostatic urethra 10 within theprostate gland 11 in between the bladder neck 12 and the externalsphincter 13. In this position, the expander 1 exerts an outward radialforce against the walls of the prostatic urethra 10 expanding theurethra to allow flow of urine. Due to the sinusoidal ring design, theoutward radial force is greatest at each end of the expander, adjacentthe transition zones of the prostatic urethra, where the greatest amountof diseased tissue is located. In addition, due to the design of theexpander, the contact area between the struts and prongs of the expanderand the wall of the prostatic urethra is minimised so that the seminalducts 15 are not obstructed by the walls of the expander. In addition,as the expander does not have any circumferential struts, removal of theexpander is facilitated.

FIG. 5 is a picture of the expander of the invention inserted into theprostatic urethra of a cadaver, showing the proximal end of the expanderin the foreground and the distal end of the expander in the backgroundabutting the bladder neck. The picture illustrates how the struts of theexpander are invaginated into the wall of the prostatic urethra.

Referring to FIG. 6, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. In this embodiment, the expander20 has five distal prongs 4 and five proximal prongs 7, and the use ofthis embodiment is the same as that described with reference to theprevious embodiment.

Referring to FIG. 7, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. In this embodiment, the expander30 has three distal prongs 4 and three proximal prongs 7, and islongitudinally inwardly tapered towards the distal end 3 with the strutshaving an angle of between 5° and 15° with the longitudinal axis of theexpander when in a relaxed state. The use of this embodiment is the sameas that described with reference to the previous embodiment.

Referring to FIG. 8, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. In this embodiment, the expander40 has three distal prongs 4 and three proximal prongs 7, and the strutsare curved outwardly along their length so that the expander has asubstantially barrel shape along its length. The use of this embodimentis the same as that described with reference to the previous embodiment.

Referring to FIG. 9, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. In this embodiment, the expander50 has three distal prongs 4 and three proximal prongs 7, and the strutsare curved inwardly along their length so that the expander has asubstantially waisted shape along its length, with a narrowed centralportion 51 and slightly widened ends 3, 6. In addition, the apices 5, 8at each end are flared outwardly. The use of this embodiment is the sameas that described with reference to the previous embodiment.

Referring to FIG. 10, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. In this embodiment, the expander60 has five distal prongs 4 and five proximal prongs 7, and the apices 5at the distal end 3 are flared outwardly. The use of this embodiment isthe same as that described with reference to the previous embodiment.

Referring to FIG. 11, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. In this embodiment, the expander70 has three distal prongs 4 and three proximal prongs 7. The apices 5at the distal end 3 are formed into loops 71 that project radiallyinwardly, and the apices 8 at the proximal end 6 are formed into loops72 that project radially outwardly. The use of this embodiment is thesame as that described with reference to the previous embodiment.

Referring to FIGS. 12 and 13, there is illustrated an elevational viewof an expander according to an alternative embodiment of the inventionin which parts described with reference to the previous embodiments areassigned the same reference numerals. In this embodiment, the expander80 has three distal prongs 4 and three proximal prongs 7. The apices 5at the distal end 3 are formed into loops 81 that project radiallyinwardly, and the apices 8 at the proximal end 6 are formed into loops82 that project radially outwardly. In addition, the longitudinalposition of the distal and proximal prongs is offset enabling the loops81 to dovetail when the expander is in a contracted orientation (shownin FIG. 13). The use of this embodiment is the same as that describedwith reference to the previous embodiment.

Referring to FIG. 14, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. In this embodiment, the expander90 has three distal prongs 4 and three proximal prongs 7. The apices 5at the distal end 3 are formed into loops 91 that project along alongitudinal axis of the expander, and the apices 8 at the proximal end6 are formed into loops 92 that project along a longitudinal axis of theexpander. In addition, the struts are curved outwardly. The use of thisembodiment is the same as that described with reference to the previousembodiment.

Referring to FIG. 15, there is illustrated an expander according to analternative embodiment of the invention in which parts described withreference to the previous embodiments are assigned the same referencenumerals. In this embodiment, the expander 100 is formed of a nitinolwire that has a varying thick ness along its length, with the portionsof the wire forming the distal prongs 4 being thicker that the portionof the wire that forms the proximal prongs 7. The use of this embodimentis the same as that described with reference to the previous embodiment.

Referring to FIG. 16, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. In this embodiment, the expander110 has three distal prongs 4 and three proximal prongs 7. The apices 5at the distal end 3 comprise M-shaped loops 111 that project along alongitudinal axis of the expander. In addition, the nitinol wire has anend 112 that extends beyond the distal end 3 of the expander andcomprises a terminal barb 113 for fixing the expander in place(anchoring element). The use of this embodiment is the same as thatdescribed with reference to the previous embodiment.

Referring to FIG. 17, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. This embodiment is similar to thatof FIG. 16 with the exception that the end of the nitinol wire forms twohelical loops 114 and terminates in a barb 113 for fixing the expanderin place (anchoring element). The use of this embodiment is the same asthat described with reference to the previous embodiment.

Referring to FIG. 18, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. In this embodiment, the expander120 has three distal prongs 4 and three proximal prongs 7 and is formedfrom a nitinol wire that overlaps at a joining point 121 and has ends122 and 123 that extend longitudinally beyond the ends of the expanderand comprise terminal barbs 124 for fixing the expander in place(anchoring element). The use of this embodiment is the same as thatdescribed with reference to the previous embodiment.

Referring to FIG. 19, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. In this embodiment, the expandercomprises an anchoring element 126 disposed on a longitudinal strut 9,the anchoring element comprising a strut-embracing sleeve 127 andupwardly projecting barbs 128.

Referring to FIG. 20, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. This embodiment is similar to thatof FIG. 18 with the exception that the ends 122 and 123 extendsubstantially circumferentially around each end of the expander andcomprise terminal barbs 124 for fixing the expander in place. The use ofthis embodiment is the same as that described with reference to theprevious embodiment.

Referring to FIG. 21, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. In this embodiment, the expander130 has three distal prongs 4 and three proximal prongs 7, and islongitudinally inwardly tapered towards the distal end 3 with the strutshaving an angle of between 5 and 15 degrees with the longitudinal axisof the expander when in a relaxed state. In addition, two adjacentstruts 131 are cranked inwardly intermediate their ends providing adifferent angular spacing between the struts. The use of this embodimentis the same as that described with reference to the previous embodiment.

Referring to FIG. 22, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. In this embodiment, the expander150 is substantially the same as the expander illustrated in FIG. 1 withthe exception that the expander comprises two distal and proximal prongs4, 7 instead of three. The operation of this embodiment is the same asthe embodiment of FIG. 1.

Referring to FIG. 23, there is illustrated the expander of FIG. 22having anchoring elements 126 disposed on longitudinal struts 9. Eachanchoring element 126 comprises a sleeve 127 that embraces a strut 9 anda pair of barbs 128 that project away from the strut at right angles toeach other.

Referring to FIG. 24, there is illustrated an elevational view of anexpander according to an alternative embodiment of the invention inwhich parts described with reference to the previous embodiments areassigned the same reference numerals. In this embodiment, the expander150 is substantially the same as the expander illustrated in FIG. 22with the exception that the apices of the distal prongs 4 are rounded.

Referring to FIGS. 25 to 28, there is illustrated a number ofembodiments of anchoring elements 126, each comprising a sleeve 127configured to embrace a strut 9 of an expander of the invention, andhaving barbs 128 that project away from the strut and when in-situengage a wall of a body lumen. In the embodiment of FIG. 25, the barbs128 are mounted at each end of a top of the sleeve 127 and projectupwardly away from the strut at an angle of roughly 45 to the strut. Inthe embodiment of FIG. 26, one of the barbs 128 projects from a top ofone end of the sleeve 127 and the other barb 128 projects from a bottomof an opposite end of the expander. In the embodiment of FIG. 27, thebarbs 128 are cut-out from the top of the sleeve 127. In the embodimentof FIG. 28, a wire 129 is mounted to an inside of the sleeve 127 witheach end of the wire 129 projecting proud of the sleeve forming thebarbs 128.

Referring to FIGS. 29 to 31, there is illustrated a delivery device fordelivering an expander of the invention to a target site within a bodylumen, in this case delivery to the prostatic urethra. The device 200comprises a handle 201, a delivery tube 202 having a having a hollowdistal end 203 remote from the handle 201 configured to receive anexpander of the invention in a contracted orientation, and an ejectionelement 205 operatively connected to the handle 201 and operable toeject a stent from the open end of the delivery tube. In more detail,the ejection means 205 comprises a shunt mechanism having a distal end206 operatively connected to actuation means 207 on the handle and aproximal end disposed adjacent the distal end 203 of the tube 202. Inuse, the shunt mechanism is retracted and the expander 1 is compressedmanually into a contracted shape and inserted into the hollow distal endof the delivery tube (FIG. 30). The delivery tube is then inserted intothe urethra through the penis and advanced along the urethra until thedistal end of the delivery tube is located within the prostatic urethra10. The actuation means 207 on the handle is then actuated to extend theshunt mechanism and eject the expander 1 from the delivery tube into theprostatic urethra, where it expands to exert a radially outward pressureagainst the wall of the prostatic urethra (FIG. 31). The delivery tubeis then retracted from the urethra.

Referring to FIG. 32, there is provided a detailed elevational view ofpart of the delivery device 200 of FIG. 29. In this embodiment, theejection element 205 includes a distal head 210 having a triangularcross-section and configured to fit within a lumen of the expander whenit is mounted within the delivery tube 202. Each of the three faces ofthe head 210 include a projection 211 together forming a jig forpositioning and engaging the expander within the delivery tube, eachprojection 211 being configured to engage an apex of a proximal prong ofthe expander. The manner of operation is the same as that described withreference to the embodiment of FIGS. 29 to 31, with the exception thatthe jig engages the expander enabling the ejection element both push andpull the expander along the delivery tube. This enables a surgeonpartially eject the expander into the body lumen and then retract theexpander if they feel that it is not in the correct position.

Referring to FIG. 33A to 33D, there is illustrated a delivery device ofthe invention 300 in use delivering an expander of the invention 1 intothe prostatic urethra 10 which is surrounded by the prostate gland 11and disposed distally of the bladder 301. The delivery device 300includes a cystoscope 302 disposed concentrically within a lumen of thedelivery device 300 and having a distal end substantially flush with adistal end of the delivery tube 202. As shown in FIG. 33A, the expanderis mounted within the delivery tube 202 with the cystoscope 302projecting through a lumen of the expander. The cystoscope comprises alight that illuminates the urethra distally of the end of the deliverydevice, thereby assisting a surgeon remotely image the urethra prior todeployment of the expander (FIG. 33B), and image the urethra andexpander during deployment (FIG. 33C), and after deployment (FIG. 33D),of the expander.

Referring to FIG. 37, a method of treating benign prostatic hyperplasia(BPH) is illustrated, in which an expander 300 is implanted into theprostatic urethra 310 between the bladder neck 312 and the externalsphincter 313. The expander is capable of self-expansion between aradially contracted configuration (not shown, but employed duringdeployment) and a radially expanded configuration (shown) in which theexpander dilates the prostatic urethra thereby relieving the patient ofsome of the symptoms of benign prostatic hyperplasia, in particular itwidens the narrowed urethra, providing less resistance to urine duringurination and allows the urine to pass through the diseased prostaticurethra (whereas before it would have encountered a narrowed, highpressure lumen). The expander is configured to fit in the prostaticurethra between the bladder neck 312 and external sphincter 313, so thatit does not inhibit the function of either. As ejaculation requires thebladder neck to tonically contract and the external sphincter to spasm,the expander when properly positioned between the bladder neck andexternal sphincter allows for both of these functions, and therebyaddresses one of the drawbacks of known implants for treating BPH,impaired ejaculation and sexual dysfunction. Moreover, as the functionof the bladder neck is not compromised when the expander is in-situ,urine does not gather for long periods in the prostatic urethra therebypreventing encrustation of the expander. In addition, the expender isconfigured such that when deployed in-situ within the prostatic urethraand correctly positioned, blocking of the verumontanum 315 (andsubsequent sexual dysfunction) is avoided. To this end, a proximal endof the expander 300 includes a suitably shaped cut-out 316 whichprevents the sidewall of the expander 300 coming into contact with theverumontanum 315. In this embodiment, the expander 300 is not restrictedto the undulating ring structure of previous embodiments, but maycomprise any form of body such as for example the mesh-type bodiescommonly employed in stents, or indeed any other type of body that iscapable of adjustment between a radially contracted orientation suitablefor delivery and a radially expanded orientation capable of dilating theprostatic urethra while allowing flow of urine.

Referring to FIG. 38, an expander of the invention is shown deployed inthe prostatic urethra of a patent with BPH, between the bladder neckmuscle and the external sphincter. This figure shows how the deviceaccommodates the verumontanum between two prongs of the expander in thedistal prostatic urethra, while the proximal end of the device isconfigured such that one of the prongs pushes the transition zone of theprostate gland away from the lumen of the prostatic urethra.

Equivalents

The foregoing description details presently preferred embodiments of thepresent invention. Numerous modifications and variations in practicethereof are expected to occur to those skilled in the art uponconsideration of these descriptions. Those modifications and variationsare intended to be encompassed within the claims appended hereto.

What is claimed is:
 1. A method of treating benign prostatic hyperplasiain a mammal, which method employs an implantable biocompatible expanderconfigured for resilient deformation and self-expansion from a radiallycontracted orientation suitable for transluminal delivery through aurinary duct to a radially expanded orientation capable of effectingin-situ dilation of the prostatic urethra, wherein the expander isconfigured to fit within the prostatic urethra between the bladder neckand the external sphincter and span at least 50% of the length of theprostatic urethra between the bladder neck and external sphincter, themethod comprising the steps of implanting the expander into theprostatic urethra at a target location between the bladder neck and theexternal sphincter, whereby the expander in the radially expandedorientation effects in-situ dilation of the prostatic urethra betweenthe bladder neck and the external sphincter without blocking theverumontanum, in which the implantable biocompatible expander is formedfrom a single elongated undulating ring, in which the single elongatedundulating ring has three distal prongs and three proximal prongsproviding a triangular cross-section that matches lateral triangularrecesses of the urethra, allowing for differential flexing of theexpander during use.
 2. A method according to claim 1, and comprisingthe steps of: delivering the expander in a radially contractedorientation through the urethra to the target location within theprostatic urethra between the bladder neck and the external sphincter;and allowing the expander to expand at the target location to a radiallyexpanded orientation against the wall of the prostatic urethra with itsproximal three prongs sitting anatomically in the triangularly shapeddistal urethra.
 3. A method according to claim 1, in which the expanderis configured to anatomically conform to the lumen of the prostaticurethra.
 4. A method according to claim 1, in which the length of thesingle elongated undulating ring is at least 10% greater than the widthof the single elongated undulating ring when in a relaxed expandedstate.
 5. A method according to claim 1, in which the single elongatedundulating ring is a sinusoidal ring.